1719 results about "Noise power" patented technology

A method comprises processing M subband communication signals and N target-cancelled signals in each subband with a set of beamformer coefficients to obtain an inverse target-cancelled covariance matrix of order N in each band; using a target absence signal to obtain an initial estimate of the noise power in a beamformer output signal averaged over recent frames with target absence in each subband; multiplying the initial noise estimate with a noise correction factor to obtain a refined estimate of the power of the beamformer output noise signal component in each subband; processing the refined estimate with the magnitude of the beamformer output to obtain a postfilter gain value in each subband; processing the beamformer output signal with the postfilter gain value to obtain a postfilter output signal in each subband; and processing the postfilter output subband signals to obtain an enhanced beamformed output signal.

An efficient and non-iterative 3D post processing method and system is proposed for mosquito noise reduction, block localization and correction in DCT block-based decoded images. The 3D post processing is based on a simple classification that segments a picture in multiple regions such as Edge, Near Edge, Flat, Near Flat and Texture regions. The proposed technique comprises also an efficient and shape adaptive local power estimation for equivalent additive noise and provides simple noise power weighting for each above cited region. Temporal filtering configurations using Minimum Noise Variance Criterion are proposed for reducing temporally varying coding artifacts. A Minimum Mean Square Error or Minimum Mean Square Error-like noise reduction with robust and effective shape adaptive windowing is utilized for smoothing mosquito and/or random noise for the whole image, particularly for Edge regions. The proposed technique comprises also signal domain histogram analysis based Block Localization and adaptive edge based Block artifact correction. Finally, is also proposed an optional adaptive detail enhancer which can enhances the luminance signal in eight directions differently.

A wireless communication apparatus wherein the data amount of feedback information can be reduced, while a high throughput being maintained. In this apparatus, a CSI (Channel State Information) processing part (38) generates a CSI frame based on an SNR (Signal power to Noise power Ratio) for each of measured subcarriers, and a CSI transmission control part (39) generates a timing signal and control information required for generating the CSI frame, and controls the CSI processing part (38). The CSI processing part (38) generates a first frame (CSI1) which comprises the CSI of a subcarrier whose SNR variation amount is less than a threshold value, in a generation period that is greater than the generation period of a second frame (CSI2) comprising the CSI of a subcarrier whose SNR variation amount is equal to or greater than the threshold value.

The invention provides a new approach which is better suited to FFT design as applied to multicarrier modulation systems such as OFDM. The signals are scaled so that overflow, rather than being completely avoided, occurs with low probability throughout the IFFT and FFT structures. The size of the error that results from an overflow depends on how overflow is handled in the DSP. To minimize the degradation, overflow should result in saturation of the value at the maximum positive or negative value option. This is equivalent to clipping the signal. Using the new technique, signals within the FFT structure are scaled to balance the effect of clipping and round-off. Clipping may result in comparatively large errors in a few signal values but because of the spreading effect of the FFT and because OFDM systems typically include error coding/correction, system performance depends on the total error or, in other words the total noise power, across all of the FFT outputs rather than on any individual value.

A ringing area detector classifies the input image into two regions: a mosquito noise region (i.e. filtering region) and a non-mosquito noise region (i.e. non-filtering region), and uses this classification information to adaptively remove the mosquito noise in a mosquito noise reduction system. The mosquito noise reduction system includes a ringing area detector, a local noise power estimator, a smoothing filter, and a mixer. The ringing area detector includes an edge detector, a near edge detector, a texture detector, and a filtering region decision block. The ringing detection block detects the ringing area where the smoothing filter is to be applied. The local noise power estimator controls the filter strength of the smoothing filter. The smoothing filter smoothes the input image. The mixer mixes the smoothed image and the original image properly based on the region information from the ringing area detection block.

Hands-free phones with voice activity detection using a comparison of frame power estimate with an adaptive frame noise power estimate, automatic gain control with fast adaptation and minimal speech distortion, echo cancellation updated in the frequency domain with stepsize optimization and smoothed spectral whitening, and echo suppression with adaptive talking-state transitions.

An apparatus for and method of generating normalized soft decision information output from an inner decoder (i.e. equalizer) in a communications receiver. The invention is operative to normalize the soft decision information before it enters a soft outer decoder. The normalization is performed using a noise power estimate that is dynamically calculated in response to changing noise statistics on the channel. The normalized soft decision output is then applied to the soft outer decoder thus realizing maximum performance therefrom. The noise power estimate is derived from the training sequence and/or the data portion of the received signal. Both types of estimates are calculated. A binary or smoothly weighted average is calculated using both types of estimates. The weighting factor is determined based on one or more performance metrics, such as the Signal to Noise Ratio (SNR).

Provided is a transmitting/receiving apparatus and method for an IDMA system. The receiving apparatus includes a channel estimator, an estimator, and a determiner. The channel estimator estimates a channel using a multi-user signal received through at least one RX antenna. The estimator estimates the noise power and the signal power for each transmission layer of each user by using the estimated channel value from the channel estimator. The determiner determines the number of transmission layers for each user and an MCS level for each transmission layer by using the signal power and the noise power estimated by the estimator.

A method for carrying out channel equalization in a radio receiver wherein an impulse response is estimated, noise power is determined by estimating a co-variance matrix of the noise contained in a received signal before prefiltering, and tap coefficients of prefilters and an equalizer are calculated. The method comprises determining the noise power after prefiltering by estimating a noise covariance matrix, after which input signals of the channel equalizer are weighted by weighting coefficients obtained from the noise covariance estimation.

A method and apparatus for estimating interference and noise power in an orthogonal frequency division multiplexing/orthogonal frequency division multiple access/discrete multi-tone (OFDM/OFDMA/DMT) system is disclosed. A correlator correlates a plurality of sub-carriers with a preset reference sequence on an element-by-element basis and outputs a result of the correlation. A signal noise producer calculates a difference between a correlation value associated with each of the plurality of sub-carriers output from the correlator and a correlation value produced from at least one adjacent sub-carrier and outputs a result of the calculation. An interference and noise power producer produce interference and noise power from the difference between the correlation values calculated by the signal noise producer.

A wireless communication apparatus compensates for phase and amplitude imbalances existing among transmit and receive branches, while also preventing likelihood information and SNR estimation error produced by such imbalance compensation. In an apparatus having a plurality of transmit and receive antennas and respective branches for each antenna, a calibration processor multiplies receive signals in each receive branch by antenna calibration coefficients, in order to correct phase and amplitude imbalances existing among the receive branches. A transmit beamforming matrix estimator then estimates a transmit beamforming matrix by using the multiplied receive signals. An estimator then solves for estimated values such as the noise power, likelihood information, and channel waveform equalization values for each receive branch, and in addition, derives a final estimated value that takes the multiplication by correction coefficients into account when averaging the estimated values for each receive branch or when computing a weighted average according to likelihood.

A code-division-multiple-access (CDMA) system employing spread-spectrum modulation. The CDMA system has a base station (BS), and a plurality of subscriber units. The signals transmitted between the base station and subscriber unit use spread-spectrum modulation. The improvement apparatus for adaptive forward power control (APC) from a base station (BS) to a subscriber unit (SU), includes sending from the base station, using spread-spectrum modulation, a BS-spreading code on a forward channel. The subscriber unit despreads the BS-spreading code on the forward channel as a despread signal, determines a first power level Pd which includes power of the despread signal plus noise and a second power level PN, which includes despread-noise power. The subscriber unit determines a first error signal e1, from the first power level Pd, the second power level PN, and a required signal-to-noise ratio SNRREQ for service type, and a second error signal e2, from a measure of total received power Pr and an automatic gain control (AGC) set point Po. The subscriber unit forms a combined error signal from the first error signal e1, the second error signal e2, a first weight a1 and a second weight a2, and hard limits the combined error signal to form a single APC bit. The APC bit is transmitted to the base station. In response to the APC bit, the base station adjusts transmitter power to the subscriber unit.

Methods are described for identifying a dominant impairment on a communication channel impaired by an interference issue. The methods include systematic examination of total power loading, systematic examination of signal power reduction, statistical examination of communication channel noise power, and systematic examination of interleaver effectiveness. Each relates to automatically diagnosing and characterizing distortion-based interference issues by monitoring the performance of a communication channel during a testing procedure. These methods enable a technician or engineer to remotely diagnose distortion-based interference issues relatively quickly without having to use external test equipment and without having to deploy technicians to various locations within the cable plant. A system by which these methods can be implemented is also disclosed.

Disclosed is an adaptive downlink packet transmission method for a multicarrier Code Division Multiple Access (MC-CDMA) system. The method can allocate radio resources efficiently according to the variations of channel conditions for each user terminal, allocate transmission power appropriately according to the interference from the same cell, and minimize interference to adjacent cells. The adaptive downlink packet transmission method includes the steps of: a) estimating a signal-to-interference-and-noise ratio (SINR) in a user terminal after channel equalization and despreading by measuring a downlink pilot channel; b) measuring an average interference factor and an average noise power; and c) allocating radio resources adaptively in the central station by determining transmission slots in a transmission frame, the number of spreading codes to be used in each transmission slot, symbol energy for each spreading code, and a transmission method, until transmission slots and packets to be allocated are not available.

An efficient and non-iterative post processing method and system is proposed for mosquito noise reduction in DCT block-based decoded images. The post-processing is based on a simple classification that segments a picture in multiple regions such as Edge, Near Edge, Flat, Near Flat and Texture regions. The proposed technique comprises also an efficient and shape adaptive local power estimation for equivalent additive noise and provides simple noise power weighting for each above cited region. An MMSE or MMSE-like noise reduction with robust and effective shape adaptive windowing is utilized for smoothing mosquito and/or random noise for the whole image, particularly for Edge regions. Finally, the proposed technique comprises also, for chrominance components, efficient shape adaptive local noise power estimation and correction.

The invention provides an unmanned aerial vehicle signal processing device and a processing method thereof. The device comprises a receiving module (1), a monitoring module (2), an early warning module (3), an interference module (4) and a transmitting module (5). The early warning module (3) comprises a storage unit (10) which stores unmanned aerial vehicle frequency domain data and a comparison unit (11) which compares current frequency domain data transmitted by a frequency spectrum analysis unit (9) with the unmanned aerial vehicle frequency domain data stored in the storage unit (10). The early warning module (3) alarms when the comparison result is in the preset range. The interference module (4) comprises a baseband signal generator (12) which sets baseband signal frequency, an interference modulator (13) which modulates a baseband signal into a noise signal, a working amplifier (14) which increases noise power and a combiner (15) which combines different noise frequency bands. Close-up flight of an unmanned aerial vehicle can be warned in advance by detecting working frequency range of the unmanned aerial vehicle, and close-up flight of the unmanned aerial vehicle to the protected security area can be prevented.

A system detects a speech segment that may include unvoiced, fully voiced, or mixed voice content. The system includes a digital converter that converts a time-varying input signal into a digital-domain signal. A window function passes signals within a programmed aural frequency range while substantially blocking signals above and below the programmed aural frequency range when multiplied by an output of the digital converter. A frequency converter converts the signals passing within the programmed aural frequency range into a plurality of frequency bins. A background voice detector estimates the strength of a background speech segment relative to the noise of selected portions of the aural spectrum. A noise estimator estimates a maximum distribution of noise to an average of an acoustic noise power of some of the plurality of frequency bins. A voice detector compares the strength of a desired speech segment to a criterion based on an output of the background voice detector and an output of the noise estimator.

Hands-free phones with voice activity detection using a comparison of frame power estimate with an adaptive frame noise power estimate, automatic gain control with fast adaptation and minimal speech distortion, echo cancellation updated in the frequency domain with stepsize optimization and smoothed spectral whitening, and echo suppression with adaptive talking-state transitions.

A method for utilizing user feedback to dispatch user in a wireless multi-user MIMO communication system, including: selecting a user who synchronously receives services in multi-user MIMO transmission by a base station and each data stream number assigned to the selected user as a dispatched result, generating s pre-coding matrix based on obtained dispatched result for selected user; multiplying the pre-coding matrix and user data stream to generate a data sequence after pre-coding; generating a pilot signal for the selected user, and sending the generated pilot signal and the generated pre-coding data sequence to a user end; estimating a signal power and an interfere power when the user end receives the pilot signal, and estimating a noise power; determining whether there is a need to reduce the user number synchronously serviced by the multi-user MIMO communication system based on the obtained signal power, interfere power and noise power, and feeding back the determined result to the base station; adjusting the user number synchronously serviced by the multi-user MIMO communication system by the base station based on the received feedback result.